Orthogonal Wave Research Articles

Deaf band-based prediction of Dirac cone in acoustic metamaterials

Through an alternative paradigm, a predictive design of a Dirac-like point is introduced in a linear periodic metamaterial for the spatial guidance of acoustic waves. Dirac conelike dispersion at the Г point (for k→=0) in a Brillouin zone is called a “Dirac-like cone,” which seldom occurs due to accidental degeneracy. However, a deaf band-based predictive model shows incredible potential to achieve an engineered Dirac cone at a predictive pivoted frequency. A targeted Dirac cone at a higher frequency is carried out in this article validating the orthogonal energy transport in a spiral pattern. The dominance of asymmetric deaf band modes triggers total internal reflection and guiding of acoustic waves inside phononic crystals. To elucidate the versatility of this methodology, experimental validation of orthogonal wave transport is presented.

Compensating Sources Method for Analyzing an Inhomogeneous Periodic Radiating Array

Abstract—A method for solving boundary problems of the electrodynamics of infinite inhomogeneous two-dimensional periodic arrays is proposed: a compensating sources method. The method represents the fields exciting and scattered by each elementary emitter of the array as expansion of a system of vector orthogonal waves. The concept of a compensating source is introduced, which is associated with an array element and creates a field in space described by a given scattered wave amplitude vector. The problem of excitation of an infinite array by a compensating source is solved, and its Green’s function is obtained that relates the amplitudes of the exciting and scattered waves to the compensating source. A scheme is proposed for solving the boundary problem for an array with defects in the form of elements having a scattering operator different from the that of an element of a regular array. The solution to the problem of an array with an emitter removed is considered.

Design of a Portable Orthogonal Surface Acoustic Wave Sensor System for Simultaneous Sensing and Removal of Nonspecifically Bound Proteins.

One challenge for current surface acoustic wave (SAW) biosensors is reducing nonspecific adsorption. A device propagating Rayleigh and shear horizontal surface acoustic waves in orthogonal directions fabricated in ST quartz has the capability of achieving simultaneous detection and nonspecific binding (NSB) protein removal. Current measurement methods for a SAW sensor system based on this device require large-size and expensive equipment such as a vector network analyzer (VNA), signal generator, and frequency counter, which are not suitable for portable, especially point-of-care, applications. In this work, a portable platform based on a direct digital synthesizer (DDS) is investigated for the orthogonal SAW sensor, integrating signal synthesis, gain control, phase/amplitude measurement, and data processing in a small, portable electronic system. This prototype was verified for both stability and repeatability, and the results matched very well with VNA measurements. Finally, system performance in real-time sensing and NSB removal was evaluated.

Bifunctional circularly-polarized lenses with simultaneous geometrical and propagating phase control metasurfaces

Achieving different and arbitrary phase distributions for left-handed (LH) and right-handed (RH) circularly polarized (CP) waves, especially in transmission cases, is very important in designing CP lenses. Here, a strategy to control the propagating and geometrical phases simultaneously and independently is proposed by using a four-layered element. The element is a perfect transparent half wavelength plate, which controls the propagating phase by changing the structural size at both orthogonal polarizations and geometrical phase via rotating the structures. To verify the effectiveness of the modulation, we design three linear deflectors by manipulating only propagating phases, only geometrical phases and mix of them to achieve identical, symmetry and asymmetric refractions, respectively. Finally, we simulate and measure lens1 with refractions in different planes and lens2 with pencil-shape and vortex-shape beams. Our findings break the fixed relations of orthogonal CP waves for sole geometrical or propagating metasurface and then offer an effective strategy to achieve arbitrary bifunctional CP devices.

Achieving circular-to-linear polarization conversion and beam deflection simultaneously using anisotropic coding metasurfaces

An anisotropic coding metasurface (CM) is proposed for achieving circular-to-linear polarization conversion and beam deflection. Different phase coding consequences were independently achieved for two orthogonal linear polarized (LP) waves. Thus by elaborately designing coding sequences of the metasurfaces, different functions can be achieved, respectively for waves polarized along two orthogonal directions. More importantly, for circularly polarized (CP) wave, anisotropic CM can achieve circular-to-linear polarization conversion and beam deflection simultaneously. As a proof, a 1-bit anisotropic CM with 0101…/0101… and 0000…/1111… coding sequences respectively for two orthogonal LP waves was designed. The simulation results indicated that the incident CP wave is deflected into two x-polarized waves in x-o-z plane and two y-polarized waves in y-o-z plane. Both the simulation and experimental results verify the circular-to-linear polarization conversion performance of the anisotropic coding metasurfaces. The proposed anisotropic coding metasurfaces have the potential for the applications of multifunctional devices.

Four-channel volume holographic recording with linear polarization holography.

We report on four-channel volume holographic recording with linear polarization-sensitive holography. This technique is based on the null reconstruction effect (NRE) of linear polarization-sensitive holography, which means the diffraction efficiency varies with polarization states of the reading wave. The dependency of holographic reconstruction on the polarization state of the reading wave is investigated based on the vector holography theory. The NRE of a polarization-sensitive hologram written by orthogonal and nonorthogonal linear waves is achieved at a cross-angle of π/2 inside the recording media. Based on the NRE of linear polarization-sensitive holography, a four-channel volume holographic recording is experimentally demonstrated with negligible cross talk noise. The presented four-channel holographic recording scheme is expected to improve holographic storage density by an additional channel.

Data extension near-field acoustic holography based on improved regularization method for resolution enhancement

In recent years, patch near-field acoustic holography (NAH) has gradually emerged for the reconstruction of sound field radiated from large-scale sound source under the condition of small holographic aperture in engineering practice. However, this technique has not solved the problem that when the projection of large-scale sound source is located on the edge of the expanded hologram, high-precision reconstruction results are unavailable. In addition, the reconstruction of sound field is a typical inverse problem, so the existence of measurement errors makes the solution of the inverse problem be ill-posed and the accuracy of sound field reconstruction is greatly reduced. To overcome these difficulties, a new technique combining an improved method of orthogonal spherical wave superposition, data extension and modified regularization method is proposed to enhance the spatial resolution of reconstructed images. First, the sound pressure is reconstructed on an extended hologram using the improved method orthogonal spherical wave superposition and data extension. At the same time, the method modified Tikhonov regularization (MTR) is introduced to solve the edge error and other ill-posed reconstruction problems. Through iteration the accuracy of the regenerated data is improved. Finally, the extended data are used to reconstruct the sound field. The results of numerical simulation and experiments show that this technique can effectively improve the spatial resolution of the reconstructed image and the reconstruction is more robust.

X-ray micro-computed tomography and ultrasonic velocity analysis of fractured shale as a function of effective stress

Abstract Ultrasonic velocity is a key shale gas reservoir property, especially in the context of gas production or CO 2 injection for geo-sequestration. This ultrasonic velocity reflects the dynamic elastic properties of the rock, and it thus depends on the fracture morphology, which varies significantly with effective stress. However, the precise relationship between ultrasonic velocity and fractured shale morphology is only poorly understood. We thus measured P- and S-wave velocities of fractured shale in two orthogonal directions and imaged the shale with X-ray micro-computed tomography as a function of applied effective stress; and investigated how fracture morphology, P- and S-wave velocity, Young's modulus, shear velocity and Poisson's ratio are interconnected with effective stress. Clearly, most of the small fractures (the width is around 0.1 mm) closed with increasing effective stress, resulting in a different fracture size distribution, which again had a dramatic effect on the elastic rock properties. Furthermore, with increasing effective stress, P- and S-wave velocities increased significantly, such that the orthogonal waves gave a similar response at 2000 psi effective stress despite significant sample heterogeneity. We conclude that the fracture aperture, direction and network characteristics severely influence wave propagation and thus elastic properties. These results can be used to assess natural fracture networks, monitor fracture development during hydraulic fracturing, and predict fracture closure scenarios during production.

High-efficiency terahertz spin-decoupled meta-coupler for spoof surface plasmon excitation and beam steering.

Spoof surface plasmon (SSP) meta-couplers that efficiently integrate other diversified functionalities into a single ultrathin device are highly desirable in the modern microwave and terahertz fields. However, the diversified functionalities, to the best of our knowledge, have not been applied to circular polarization meta-couplers because of the spin coupling between the orthogonal incident waves. In this paper, we propose and demonstrate a terahertz spin-decoupled bifunctional meta-coupler for SSP excitation and beam steering. The designed meta-coupler is composed of a coupling metasurface and a propagating metasurface. The former aims at realizing anomalous reflection or converting the incident waves into SSP under the illumination of the right or left circular polarization waves, respectively, and the latter are used to guide out the excited SSP. The respective converting efficiency can reach 82% and 70% at 0.3THz for the right and left circular polarization incident waves. Besides, by appropriately adjusting the reflection phase distribution, many other functionalities can also be integrated into the meta-coupler. Our study may open up new routes for polarization-related SSP couplers, detectors, and other practical terahertz devices.

Radio pulsar polarization as a coherent sum of orthogonal proper mode waves

ABSTRACT Radio pulsar polarization exhibits a number of complex phenomena that are classified into the realm of ‘beyond the rotating vector model’ (RVM). It is shown that these effects can be understood in geometrical terms, as a result of coherent and quasi-coherent addition of elliptically polarized natural mode waves. The coherent summation implies that the observed tracks of polarization angle (PA) do not always correspond to the natural propagation mode (NPM) waves. Instead, they are statistical average of coherent sum of the NPM waves, and can be observed at any (and frequency-dependent) distance from the natural modes. Therefore, the observed tracks of PA can wander arbitrarily far from the RVM, and may be non-orthogonal. For equal amplitudes of the NPM waves two pairs of orthogonal polarization modes (OPMs), displaced by 45°, can be observed, depending on the width of lag distribution. Observed pulsar polarization mainly results from two independent effects: the change of mode amplitude ratio and the change of phase lag. In the core region both effects are superposed on each other, which can produce so complex behaviour as observed in the cores of PSR B1933+16, B1237+25, and J0437−4715. Change of the phase lag with frequency ν is mostly responsible for the observed strong evolution of these features with ν. The coherent addition of orthogonal natural waves is a useful interpretive tool for the observed radio pulsar polarization.

Initial Excited State and Divergence of Wave Beams as Factors Responsible for the Realization of the Wave Process that Controls the Growth of Transformation Twins

In the dynamic theory of martensitic transformations the wave mechanism of growth of martensite crystals is controlled by the overlap of wave beams of quasi-longitudinal (or longitudinal) waves that carry deformation of the “tension–compression” type in orthogonal directions. The appearance of wave beams is considered a consequence of the appearance of the initial excited (vibrational) states. The presence of the transformation twins is interpreted as the result of the matched propagation of relatively long-wave (𝓁 waves) and short-wave (s waves) displacements. With the aid of the Fourier transforms, an analysis was performed of the influence of the diffraction divergence of a pair of orthogonal wave beams on the formation of a region of their superposition, including the limiting case of narrow beams with one of the transverse dimensions of the front less than λ/2, where λ is the wavelength. The connection of the distribution of the amplitudes of spatial harmonics with the configuration of the initial excited state is discussed.

Generation of Vortex Lattices at the Liquid–Gas Interface Using Rotating Surface Waves

In this paper, we demonstrate experimentally that by generating two orthogonal standing waves at the liquid surface, one can control the motion of floating microparticles. The mechanism of the vortex generation is somewhat similar to a classical Stokes drift in linear progression waves. By adjusting the relative phase between the waves, it is possible to generate a vortex lattice, seen as a stationary horizontal flow consisting of counter-rotating vortices. Two orthogonal waves which are phase-shifted by π / 2 create locally rotating waves. Such waves induce nested circular drift orbits of the surface fluid particles. Such a configuration allows for the trapping of particles within a cell of the size about half the wavelength of the standing waves. By changing the relative phase, it is possible to either create or to destroy the vortex crystal. This method creates an opportunity to confine surface particles within cells, or to greatly increase mixing of the surface matter over the wave field surface.

Acoustic radiation simulation and pre-stress effect on compact acoustic levitation platform

In order to satisfy the requirements of precise components with tidiness, low power and high stability in the field of biological engineering, medical equipment and semiconductors etc. a pre-stress acoustic transport prototype without horn was proposed in this paper. The mechanism of levitation and transport which is driven by orthogonal waves was revealed by the analysis of waveform and squeeze film characteristics in high-frequency exciting condition; also, the electric, solid and acoustic coupled finite element method (FEM) was established to investigate the effect of pre-stress and acoustic pressure distribution in the near field. The levitation and driving capacity of near field acoustic levitation (NFAL) transport platform without horns can be proved in this experiment and further to achieve the goal of parameters optimization. The theoretical and experimental results indicate that the pre-stress has a significant effect on resonant frequency and levitating stability, the pre-stress are determined by the DC voltage offset which is related to the system working point so that we cannot increase the offset and exciting voltage unlimitedly to improve the stability. At the same time, the calculated pressure distribution of acoustic radiation can generally reflect the regional bearing capacity in near and far field for levitation. These achievements can partly solve the problem of accuracy design of prototype and thickness of gas film, supporting for accuracy close loop control of levitating height.

Deaf band based engineered Dirac cone in a periodic acoustic metamaterial: A numerical and experimental study

A Dirac-cone-like dispersion at the center of the Brillouin zone where the wave number $\stackrel{P\vec}{k}=0$ [L. Brillouin, Wave Propagation in Periodic Structures (Dover, New York, 1953)], is rare and only happens due to accidental degeneracy. At certain frequencies, the Dirac cone breaks the time-reversal symmetry of acoustic waves, which has not yet been fully explored. In this paper, even the simplest geometric microarchitecture of phononic crystals (PnCs) in a periodic structure can be modulated to obtain the accidental triple degeneracies that make a Dirac-like cone at the \ensuremath{\Gamma} point ($\stackrel{P\vec}{k}=0$). While doing so, it was observed that the frequency of a nondispersive band obtained from any arbitrary periodic structure made of similar PnCs remains unaltered. Then, a deaf band based predictive modulation of the PnCs is realized, and multiple occurrences of the Dirac-like points are demonstrated. The claims are validated using a numerical and experimental study of a baseline periodic structure having a square array of cylindrical polyvinylchloride inclusions in an air matrix. Phenomena such as orthogonal wave transport, negative refraction, and wave vortex are verified to exist at the deaf band based engineered Dirac cone.

Intraperitoneal perfusion chemotherapy and whole abdominal hyperthermia using external radiofrequency following radical D2 resection for treatment of advanced gastric cancer

Background: The peritoneum is the most frequent site of disease recurrence in gastric cancer, and the prognosis remains poor. This study assessed the role of adjuvant intraperitoneal (IP) chemotherapy with whole abdominal hyperthermia using external radiofrequency in gastric cancer patients after D2 dissection.Methods: Patients with gastric cancer who underwent gastrectomy with D2 regional lymph node dissection were enrolled in the study. Patients received IP chemotherapy with whole abdominal hyperthermia. Preheated normal saline containing 75 mg/m2 of cisplatin was delivered into the abdominal cavity through a Tenckhoff catheter at McBurney’s point. Regional hyperthermia was performed using two sets of orthogonal radiofrequency waves immediately after all saline was irrigated into the abdominal cavity. For each patient, recurrent or metastatic sites and adverse events were evaluated.Results: A total of 22 patients were finally included. All patients tolerated hyperthermia well. Only two patients experienced grade 1 superficial thermal injury. The most frequent grade 3/4 adverse events were myelosuppression, nausea/vomiting, trichomadesis and liver dysfunction. We also found IP chemotherapy with whole abdominal hyperthermia could reduce the total recurrent/metastatic rate, especially peritoneal metastasis (4.5%).Conclusions: This hypothesis-generating study indicated that IP chemotherapy with whole abdominal hyperthermia might be feasible for gastric cancer patients after D2 resection.

Dual-Band Dual-Linear-to-Circular Polarization Converter in Transmission Mode Application to <inline-formula> <tex-math notation="LaTeX">$K/Ka$ </tex-math> </inline-formula>-Band Satellite Communications

Many wireless communication applications such as satellite communications use circularly polarized (CP) signals, with the requirement for easy switching of the polarization sense between uplink and downlink. Specifically, in satellite communications, the trend is also to move to higher frequencies and integrate the receiving and transmitting antennas in one dual-band terminal. However, these simultaneous demands make the design and fabrication of the composing parts very challenging. We propose, here, a dual-band dual-linear polarization (LP)-to-CP converter that works in the transmission mode. The working principle of this polarizer is explained through an example for Ka-band satellite communications at 19.7–20.2 and 29.5–30 GHz. The LP-to-CP converter is a single panel composed of identical unit cells with a thickness of only 1.05 mm and a size of 5.3 mm $\times5.3$ mm. Due to its operation in the transmission mode, the polarizer can be combined with a simple dual-band dual-LP antenna to obtain the desired dual-band dual-CP single antenna. However, the unique property of this polarizer is yet the fact that it converts a given LP wave, e.g., x-polarization, to orthogonal CP waves at the two nonadjacent frequency bands, e.g., left-handed CP at lower band and right-handed CP at higher band. The polarizer is tested both with 20 and 30 GHz LP rectangular horns to illuminate a dual-band transmit array (TA) to obtain wide-angle steering of CP beams. The performance of the polarizer and its association with the TA is evaluated through simulation and measurements. We also present design guidelines for this type of polarizer.

Polarization-Controlled Shared-Aperture Metasurface for Generating a Vortex Beam With Different Modes

Electromagnetic waves carrying orbital angular momentum (OAM) have drawn much attention in the fields of radar detection and wireless communication. In such applications, vortex beams with multiple OAM modes need to be transmitted and received at the same time. This communication introduces the shared-aperture concept into metasurfaces for generating OAM vortex beams with different modes. Two independent geometry phase profiles on the same aperture are utilized to modulate the phase of two orthogonal linear-polarization waves. The alliance of polarization and orbit provides a routine to generate two different OAM modes simultaneously and achieves higher aperture efficiency than the conventional shared-aperture schemes. In this manner, different OAM modes can be separated easily by hardware. The simulated results validate the proposed method and structure.

Application of orthogonal dipole shear wave in the research of formation stress

In the formation stress research, the formation may be regarded as the transversely isotropic medium. The main research is horizontal direction two stresses, namely maximum and minimum stress. The orthogonal dipole shear wave logging was gained, which made it convenient to calculate the stress. This article quotes the elastic modulus and the stress relations, which derived the transversely isotropic formation stresses formula. The formation fracture pressure and the borehole stability expression were gained based on the fracture pressure elementary theory. At the same time it has also calculated many parameters such as the elastic modulus, anisotropy coefficient and so on. The orthogonal dipole shear wave logging was analyzed, which indicated that there is no need to consider formation tectonic factor. When calculating maximum and minimum stress was same based on fast and slow shear wave velocity was same, which reflected the formation assumed the isotropic. When they have the difference, it is showed that the formation assumes the anisotropy. Commonly-used the isotropic medium is one kind of the transversely isotropic medium.

Optical technologies towards improving the Far-infrared laser Polarimeter-Interferometer system on HL-2A tokamak

Since the first performance of the HCOOH laser Polarimeter-Interferometer (PIer) in 2015 HL-2A experimental campaign, several optical technologies have been applied to improve the PIer system, including: (1) Optical alignment of the HCOOH laser at the long distance was implemented by the optical setup integrated by a lens and a high-sensitivity Pyroelectric Array Camera. (2) Due to application of the orthogonal waves transmission in the PIer system, some spurious intermediate frequency (IF) might be generated in the interferometry beat signal. For this problem, an effective optical adjustment method based on the single-polarization response characteristic of the Schottky diode detector was summarized in practice. (3) For double-passing type Faraday-effect polarimeter, analysis indicated that the severe oscillation disturbance in Faraday rotation angle was mainly caused by the stray lights or the feedback lights. Experimental results on HL-2A successfully validated that the unwanted feedback lights mainly came from the detector surface and was able to be effectively suppressed by the optic-isolator which was composed of a polarizer and a quarter-wave plate.

Wideband Metasurface-Based Reflective Polarization Converter for Linear-to-Linear and Linear-to-Circular Polarization Conversion

A wideband reflective polarization converter based on metasurface is proposed in this letter. This converter can transform a linearly polarized (LP) incident electromagnetic (EM) wave into its orthogonal LP reflection wave in a lower band, and a circularly polarized (CP) reflection wave in a higher band. The unit cell of this converter is comprised of two meander lines and one cut wire printed on a dielectric substrate, backed with metallic ground sheet. The simulation results show that the y / x -polarized incident EM wave can be converted to the x/y -polarized reflected wave over a fractional bandwidth of 59.6% from 6.53 to 12.07 GHz with a polarization conversion ratio over 0.88. Besides, the y / x -polarized incident EM wave is converted to a CP reflected wave from 13.70 to 15.60 GHz (a fractional bandwidth of 13.0%). To verify the polarization conversion performance, a sample consisting of 30 × 30 unit cells is fabricated and measured. The experimental and simulation results obtained are in a reasonable agreement, which verifies the properties of the design.